Agricultural harvesting machines such as combines typically include a spreader for propelling crop residue onto a harvested field. Crop residue may include stalks, leaves and cobs separated from corn or maize; straw and chaff separated from wheat and other grasses; and stalks, leaves and pods of legumes such as soybeans. In many instances it is desirable for the crop residue to be spread as evenly as possible over the entire width of the harvested swath, to avoid problems resulting from uneven spreading, such as, but not limited to, difficulty in passage of fall tillage tools through residue clumps or thick areas; uneven insulation of the field resulting in uneven field warming and thawing and weed or crop emergence during the following planting season; and increased rodent and insect habitat.
In some cases, though, particularly where combines are used to harvest cereal grains, there may be a desire to windrow straw or other discharge for subsequent baling. Windrow discharge from the combine can be stalled or disbursed by strong winds that approach the straw perpendicular to its discharge trajectory. As a result, a secondary operation may be necessary to arrange the straw in a narrow dense formation for processing by a baling machine. In some cases, fine straw and other smaller particles that might otherwise be collected for baling are lost altogether, having been disbursed by the wind and fallen through the stubble and being too fine to be recovered by a secondary operation.
What is needed is a way to preserve and support free windrow formation of discharge exiting the harvester and to reduce scattering of straw and other materials that decreases the ability of that material to be collected for baling.